xfs: add BMAPI_NORMAP flag to perform block remapping without updating rmapbt

Add a new flag, XFS_BMAPI_NORMAP, which will perform file block
remapping without updating the rmapbt.  This will be used by the repair
code to reconstruct bmbts from the rmapbt, in which case we don't want
the rmapbt update.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -2005,10 +2005,13 @@ xfs_bmap_add_extent_delay_real(
 		ASSERT(0);
 	}
 
-	/* add reverse mapping */
-	error = xfs_rmap_map_extent(mp, bma->dfops, bma->ip, whichfork, new);
-	if (error)
-		goto done;
+	/* add reverse mapping unless caller opted out */
+	if (!(bma->flags & XFS_BMAPI_NORMAP)) {
+		error = xfs_rmap_map_extent(mp, bma->dfops, bma->ip,
+				whichfork, new);
+		if (error)
+			goto done;
+	}
 
 	/* convert to a btree if necessary */
 	if (xfs_bmap_needs_btree(bma->ip, whichfork)) {
@@ -2672,7 +2675,8 @@ xfs_bmap_add_extent_hole_real(
 	struct xfs_bmbt_irec	*new,
 	xfs_fsblock_t		*first,
 	struct xfs_defer_ops	*dfops,
-	int			*logflagsp)
+	int			*logflagsp,
+	int			flags)
 {
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	struct xfs_mount	*mp = ip->i_mount;
@@ -2849,10 +2853,12 @@ xfs_bmap_add_extent_hole_real(
 		break;
 	}
 
-	/* add reverse mapping */
-	error = xfs_rmap_map_extent(mp, dfops, ip, whichfork, new);
-	if (error)
-		goto done;
+	/* add reverse mapping unless caller opted out */
+	if (!(flags & XFS_BMAPI_NORMAP)) {
+		error = xfs_rmap_map_extent(mp, dfops, ip, whichfork, new);
+		if (error)
+			goto done;
+	}
 
 	/* convert to a btree if necessary */
 	if (xfs_bmap_needs_btree(ip, whichfork)) {
@@ -4127,7 +4133,8 @@ xfs_bmapi_allocate(
 	else
 		error = xfs_bmap_add_extent_hole_real(bma->tp, bma->ip,
 				whichfork, &bma->icur, &bma->cur, &bma->got,
-				bma->firstblock, bma->dfops, &bma->logflags);
+				bma->firstblock, bma->dfops, &bma->logflags,
+				bma->flags);
 
 	bma->logflags |= tmp_logflags;
 	if (error)
@@ -4573,7 +4580,7 @@ xfs_bmapi_remap(
 	got.br_state = XFS_EXT_NORM;
 
 	error = xfs_bmap_add_extent_hole_real(tp, ip, XFS_DATA_FORK, &icur,
-			&cur, &got, &firstblock, dfops, &logflags);
+			&cur, &got, &firstblock, dfops, &logflags, 0);
 	if (error)
 		goto error0;
 

fs/xfs/libxfs/xfs_bmap.h

@@ -120,6 +120,9 @@ struct xfs_extent_free_item
 /* Skip online discard of freed extents */
 #define XFS_BMAPI_NODISCARD	0x1000
 
+/* Do not update the rmap btree.  Used for reconstructing bmbt from rmapbt. */
+#define XFS_BMAPI_NORMAP	0x2000
+
 #define XFS_BMAPI_FLAGS \
 	{ XFS_BMAPI_ENTIRE,	"ENTIRE" }, \
 	{ XFS_BMAPI_METADATA,	"METADATA" }, \
@@ -133,7 +136,8 @@ struct xfs_extent_free_item
 	{ XFS_BMAPI_COWFORK,	"COWFORK" }, \
 	{ XFS_BMAPI_DELALLOC,	"DELALLOC" }, \
 	{ XFS_BMAPI_CONVERT_ONLY, "CONVERT_ONLY" }, \
-	{ XFS_BMAPI_NODISCARD,	"NODISCARD" }
+	{ XFS_BMAPI_NODISCARD,	"NODISCARD" }, \
+	{ XFS_BMAPI_NORMAP,	"NORMAP" }
 
 
 static inline int xfs_bmapi_aflag(int w)